Movable barrier opener with brushless dc motor

ABSTRACT

A movable barrier opener system having a multiphase brushless DC motor in the drive assembly is provided. The multiphase brushless DC motor may impart motive force to a movable barrier in response to barrier movement instructions from the barrier operator controller to the drive assembly. The barrier operator controller of the movable barrier opener system is configured to detect a back EMF of at least one winding of the multiphase brushless DC motor and determines a position of the movable barrier and/or determines a torque of the multiphase brushless DC motor in response to the detected back EMF. A position sensor and a back EMF sensor module provides actual operating parameters to the controller.

RELATED APPLICATION

This application claims the benefit of and priority from U.S.Provisional Patent Application Ser. No. 62/536,379, entitled “BRUSHLESSDC MOTOR OPERATOR,” filed Jul. 24, 2017, and naming Greg Matias andBrent Buescher, Jr. as inventors, and U.S. Provisional PatentApplication Ser. No. 62/536,385, entitled “BRUSHLESS DC MOTOR OPERATOR,”filed Jul. 24, 2017, and naming Greg Matias and Dan Punchack asinventors, and U.S. Provisional Patent Application Ser. No. 62/536,390,entitled “BRUSHLESS DC MOTOR OPERATOR,” filed Jul. 24, 2017, and namingGreg Matias as inventor, each of which is incorporated in its entiretyby reference herein for all purposes.

TECHNICAL FIELD

The present invention relates generally to movable barrier openersystems for opening and closing garage doors, gates, and other movablebarriers, in particular to movable barrier opener systems incorporatingbrushless DC motors, and even more particularly to new and improvedmethod for effecting control over such systems.

BACKGROUND

Upward acting sectional or single panel garage doors, rollup doors,gates, and other types of powered movable barriers utilize movablebarrier opener systems for facilitating control over the movement of thebarriers. A typical movable barrier opener system comprises a movablebarrier operator and a drive assembly, including a motor, for impartingmovement to the movable barrier (e.g., the garage door). The movablebarrier operator includes a controller which, typically, constitutes aprogrammable platform such as a microprocessor, microcontroller, or thelike, that is preprogrammed with the appropriate instructions and datafor carrying out the desired processing. The operation of most existingmovable barrier opening systems is typically responsive to externallytransmitted command signals from user-actuation of (i) interior orexterior building mounted consoles, in wired or wireless communicationwith the movable barrier operator, (ii) hand held or vehicle mountedwireless transmitters, and/or (iii) remotely disposed network (e.g.,Internet) access devices (e.g., Smartphones).

The movable barrier operator (or for specifically a garage door, thegarage door operator) must, in addition to its other tasks, (i) assurethat the force applied by the motor is sufficient to enable the movablebarrier (i.e.,. the garage door) to uninterruptedly travel along itsdefined path between open and closed limits, while at the same time (ii)assure that abnormal barrier travel conditions such as obstructions orother abnormal occurrences, will result in rapid interruption of thedoor travel (by motor stoppage, or motor stoppage and reversal.)

During the travel of the movable barrier, typically between a fully openand fully closed position, various motor overload conditions may occurdue, for example, to obstruction engagement, mechanical failures, orexcessive heat generation. Thus there is a continuing need to monitorand quickly respond to these and other situations resulting in motoroverload.

Furthermore, there is a need to continuously determine the location anddirection of travel of the movable barrier in order to maintaincontinuous control over the barrier, and quickly respond to situationswhich place the barrier and its surroundings in harm's way.

SUMMARY

In accordance with these and other objectives, disclosed herein is a newand improved movable barrier opener system, one incorporating amultiphase brushless DC motor, responsive to barrier movementinstructions generated by a programmable controller in the movablebarrier operator to the motor drive assembly. In addition to beingresponsive to externally generated command signals, the controller, forthe purpose of generating the barrier movement instructions, isresponsive to the receipt of the actual operating parameters (i.e.,conditions) of the multiphase brushless DC motor, which parameters maybe derived, for example, by a position sensor disposed at the output ofthe multiphase brushless DC motor and/or by a back EMF sensor modulemonitoring the back EMF generated from the excitation of the windings ofthe brushless DC motor.

In accordance with a feature of the new and improved movable barrieropening system, a method of control over the generation of the barriermovement instructions includes an initial determination as to whether anactual operating parameter is, or is not, within a tolerance of anexpected range of values, with the pre-programmed controller configuredto responsively change the barrier movement instructions in accordancewith such determination.

BRIEF DESCRIPTION OF THE DRAWINGS

Alternate embodiments of the herein described apparatus and methods ofthe present invention, as well as additional features and detailsthereof, will become readily understood from the following detaileddescription, taken in connection with the appended drawings, in which:

FIG. 1 is a functional block diagram of a movable barrier opener systemadapted for incorporation of the new and improved method and apparatusof the present invention;

FIG. 2A is a more detailed block diagram view of the movable barrieropener system of FIG. 1, illustrating the incorporation of a multiphasebrushless DC motor in the drive assembly, and the use of motorcharacteristics sensors for providing actual operating parameters, inaccordance with an aspect of the present invention;

FIG. 2B is a detailed view of a subset of features of the movablebarrier opener system of FIG. 2A, in which the drive assemblyincorporates the multiphase brushless DC motor and a screw driveassembly; and

FIG. 3 is a flowchart of a movable barrier movement control methodimplementable with the movable barrier opener system illustrated in FIG.2A.

DETAILED DESCRIPTION

Referring initially to FIG. 1, a movable barrier opener system 2comprises a movable barrier operator 6 and drive assembly 10, the outputof which is operatively associated with movable barrier assembly 8.Power supply system 4 provides the requisite electrical power to barrieroperator 6 and drive assembly 10.

As illustrated, the barrier operator 6, particularly the controller 18thereof (FIG. 2A), by way of barrier movement instructions transmittedalong, and in the direction of, communication pathway 6 a, effectscontrol of the operation of the drive assembly 10, and therefore, by wayof communication pathway 10 b, effects ultimate control of the movementof movable barrier 26 (FIG. 2A) of the movable barrier assembly 8. Thesebarrier movement instructions may be responsive to externallytransmitted command signals 1 (e.g., from user actuation of the wallconsoles, the hand held transmitters, or the remotely disposed Internetaccess) and/or, in accordance with a unique feature of the movablebarrier opening system of the present invention, responsive to theactual operating parameters (i.e., conditions) of the multiphasebrushless DC motor 24 (FIG. 2A) of drive assembly 10 transmitted to thecontroller 18 of the barrier operator 6 along, and in the direction of,communication pathway 10 a, as subsequently described in greater detail.It is to be understood that the communication pathways, particularlypathways 6 a and 10 a, may be conductive wires or cables or wirelesscommunication paths.

Referring to FIG. 2A, the power supply system 4 may include an AC source12, that, for example, comprises an electrical connection to a linecurrent source, such as an electrical plug and/or other interfaceconfigured to receive electrical power from an electrical powerdistribution grid by way of electrical sockets or the like. Power supplysystem 4 may additionally include a power supply module 14 adapted toreceive AC power from AC source 12, and configured to adjust the ACpower and rectify the AC power to DC power. The power supply module 14is configured to produce electrical power suitable for operating thecomponents of the barrier operator 6, including the controller 18, andfor operating the components of the drive assembly 10, includingmultiphase drive circuit 20 and multiphase brushless DC motor 24.

With continued reference to FIG. 2A, the barrier operator 6 includescontroller 18, a suitably programmed computer platform, such as apre-programmed microcontroller, microprocessor, or like apparatus. Thecontroller 18 is operatively coupled, and programmed to provide barriermovement instructions, to appropriate drive circuitry, specificallymultiphase drive circuit 20 of the drive assembly 10, and therefore, viawindings 23-1, 23-2, and 23-3, to multiphase brushless DC motor 24. As aconsequence, the barrier movement instructions from the controller 18provide the desired operation of the motor 24, such as preferreddirection and velocity of rotation of the output shaft of motor 24,preferred motor torque, required motor acceleration and deceleration,and the like.

The controller 18 may provide the requisite barrier movementinstructions by way of pulse width modulated drive signals forexcitation of the windings of the multiphase brushless DC motor 24.Alternatively, the controller 18 may provide packetized data to themultiphase drive circuit 20 of the drive assembly 10 which generates thedrive signals for excitation of one or more windings of the multiphasebrushless DC motor 24. in response to the packetized data.

Thus, it is to be appreciated that the barrier movement instructionsfrom controller 18 may be embodied in one or more waveforms, and/or oneor more packets of data. As such, the barrier movement instructions maybe in the form of analog or digital signals.

The controller 18 may provide the barrier movement instructions to thedrive assembly 10 in response to, and as a function of, the externallygenerated command signals 1 and/or in response to, and as a function of,sensed data constituting the actual operating parameters of the motor.For instance, and with reference to FIG. 2A, the barrier operator 6 mayalso include a back EMF sensor module 22 configured to provide a backEMF sensor signal 13 to the controller 18. From this back EMF, theprogrammed controller 18 may be able to determine numerous operatingparameters, conditions, and characteristics relevant to the motor,including motor load, motor overload, motor speed, and/or extent anddirection of motor shaft rotation, and thus the distance and directionof travel of the connected movable barrier 26. In addition, a positionsensor 28 may be coupled to the output shaft of the motor 24 to providethe motor shaft position data, and thus the movable barrier positioninformation, to the controller 18, for comparison to the movable barrierposition data provided by the sensor module 22.

The back EMF sensor module 22 comprises a sensor configured to detect aback EMF of at least one winding of the multiphase brushless DC motor 24of the drive assembly 10. The back EMF sensor module 22 mayalternatively include an array of sensors respectively configured todetect the back EMF of each one of the plurality of windings of themultiphase brushless DC motor 24.

Thus, while any number of sensors may be used for detecting the back EMFof any number of windings, in accordance with the preferred embodimentof FIG. 2A, a single EMF sensor module 22 is configured to detect afirst back EMF of winding 23-1 of the multiphase brushless DC motor 24,a second back EMF of winding 23-2 of multiphase brushless DC motor 24,and a third back EMF of winding 23-3 of multiphase brushless DC motor24. Therefore, the single sensor module 22 generates a back EMF sensorsignal 13 in response to the detected back EMF of the first winding, theback EMF of the second winding, and the back EMF of the third winding,the resulting sensor signal 13 provided by the back EMF sensor module 22to the controller 18.

In accordance with another feature of the present movable barrieropening system, the controller 18 may relate the barrier movementinstructions to the actual operating parameters by a transfer function,to create a “movable barrier profile” characterizing the physicalproperties of the movable barrier 26. For instance, the controller 18may determine tolerances for the actual operating parameters based onhistorical data over time showing a tendency of the operating parametersto remain within a certain range. This range may be the preset tolerancefor the relevant operating parameter. The controller 18 then determinesif the operating parameters are out of tolerance, thereby indicating afault condition such as an obstruction, a damaged movable barrier 26, anunsuitable movable barrier 26 for a particular multiphase brushless DCmotor 24 or other components, a motor over temperature situation, and/orthe like, and carries out the appropriate operation in recognition ofsuch out of tolerance status. An out of tolerance operating parametermay also indicate that a movable barrier position calculation that isbased on the operating parameter is less accurate than expected.

In accordance with another feature, the controller 18 may relate theactual operating parameters to an “interpretation matrix” to calculatebarrier position metrics. An interpretation matrix may comprise a lookuptable referenced by the controller 18, the look up table comprising adatabase of operative parameters corresponding to a position (and/ordirection) of the movable barrier 26. The interpretive matrix may alsocomprise machine learning features. For instance, the controller 18 maycollect movement parameters, and/or operative parameters over time andmay revise the movable barrier profile over time based on the movementparameters and/or operative parameters. The interpretation matrix maythen be changed in response to the revisions. Barrier position metricsmay include a relative and/or actual position and/or direction of amovement of the movable barrier 26.

In accordance with the embodiment of FIG. 2A, the position sensor 28 isa component of the barrier operator 6, the position sensor 28 generatinga position sensor signal 11 corresponding to the motor shaft position tothe controller 18. While both the position sensor 28 and the back EMFsensor module 22 are depicted in FIG. 2A, one may appreciate that theuse of both sensor assemblies may not always be necessary, dependingupon the need for redundancy.

In various embodiments, a position sensor 28 comprises a sensor thatgenerates a position sensor signal 11 in response to a “detectionaction”. For example, a detection action may include determining anobstruction in a path of the movable barrier 26. For instance, theposition sensor 28 may include an optical beam sensor that determineswhen an obstruction is positioned in a path of a movable barrier 26 inresponse to the obstruction interfering with an optical beam.

In further instances, a detection action may include determining thatthe movable barrier 26 is at an end point of travel. For instance, theposition sensor 28 may comprise a switch configured to actuate inresponse to the movable barrier 26 reaching an end point of travel.Thus, in various instances, the position sensor 28 may determine aposition of an obstruction, and in further instances, the positionsensor 28 may determine a reference position of a movable barrier 26corresponding to an end point of travel.

The position sensor 28 may provide a position sensor signal 11 to thecontroller 18 which uses the position sensor signal 11 to “index” theactual operating parameters against the end points of the movablebarrier 26 travel. In other applications, no position sensor 28 isutilized and such indexing is performed by monitoring a back EMF sensormodule 22 and determining that a sensed back EMF corresponds to a torqueof a multiphase brushless DC motor 24 having moved a movable barrier 26to a hard stop against an end point of the movable barrier 26 travel.Thus, indexing may be performed by a controller 18 in connection withthe back EMF sensor module 22 and the position sensor 28 may not beneeded for that purpose.

As used herein, to index the operative parameters against the end pointsof the movable barrier 26 travel means to provide a static terminal endof the possible position of the movable barrier 26 such that relativeposition and/or direction data provided in connection with the operativeparameters may be mapped to a physical location of the movable barrier26 relative to a fixed spatial location. Thus, the relative positionand/or direction data provided in connection with the actual operatingparameters may be made to be spatially oriented so that the actualposition and or direction relative to the end of travel of the movablebarrier 26 and relative to an “opening” and/or “closing” direction iscalculable by the controller 18 based on the operative parameters. Whena position of the movable barrier 26 is related to a fixed spatiallocation such as an endpoint of the movement of the movable barrier 26,the position or direction data related to the fixed spatial locationmakes up a portion of the so-called “barrier position metrics” includingan actual position and/or direction of a movement of the movable barrier26.

The controller 18 may relate the barrier position metrics to a table oftransition states. For instance, an end point of the movement of themovable barrier 26 is a transition state. At this transition state, thecontroller 18 directs the movable barrier 26 to transition from movementto non-movement. Other transition states may include a position along atravel of a movable barrier 26 at which the movable barrier 26 speeds upor slows down, or an associated torque changes such as due to themovable barrier 26 traveling through a path. Moreover, transition statesmay be proximate to other transition states, for instance, a transitionstate corresponding to a slowing of the movable barrier 26 mayimmediately precede a transition state corresponding to a transitionfrom movement to non-movement. In this manner, a movable barrier 26 maymore gradually start or stop movements. As such, a movable barrier 26may be said to be “soft start” or “soft stop.”

Attention is now directed to aspects of the drive assembly 10. Asmentioned, the drive assembly 10 includes a multiphase drive circuit 20and the multiphase brushless DC motor 24. The multiphase drive circuit20 comprises a circuit configured to receive barrier movementinstructions from the controller 18 and generate winding drive currentshaving waveforms tailored to generate particular behavior of themultiphase brushless DC motor 24 corresponding particularly to aspecific barrier movement instruction received from the controller 18.The multiphase drive circuit 20 may adapt the winding drive currentsover time to bring the actual operating parameters in closer correlationwith the barrier movement instructions. Such machine learning and/orfeedback may be accomplished by the controller 18 in connection withcalculating a transfer function relating the barrier movementinstructions to the actual operating parameters.

The multiphase drive circuit 20 may generate a separate winding drivecurrent for each winding of the multiphase brushless DC motor 24. FIG.2A depicts a multiphase drive circuit 20 delivering a first windingdrive current via a first winding 23-1 to multiphase brushless DC motor24, a second winding drive current via a second winding 23-2 tomultiphase brushless DC motor 24, and a third winding drive current viaa third winding 23-3 to multiphase brushless DC motor 24.

While the brushless DC motor 24 depicted in FIG. 2A has three sets ofwindings, it is also contemplated that a different number of windingsmay also be acceptable. Moreover, the brushless motor comprises adirect-current (DC) type. The brushless DC motor may be driven such thatseparate driving waveforms associated with each separate windingcollaborate to cause the motor to rotate with a torque, direction,velocity, acceleration, and/or other characteristic as desired and undercontrol of the controller 18 in response to the barrier movementinstructions.

Attention is now directed to the movable barrier assembly 8. Referringto FIG. 2A, the movable barrier assembly 8 includes a movable barrier 26that is movable in response to the control instructions from driveassembly 10. The movable barrier 26 may be a garage door, gate, or anyof the different types of powered movable barriers.

The movable barrier 26 may be configured to be moved between its limitpositions by the brushless DC motor 24 via an interconnection betweenthe rotating output shaft of the motor 24 and the movable barrier 26. Incertain applications, this interconnection is an intercoupled gearingarrangement. In other applications, the interconnection is a chaindrive, in which a sprocket attached to the multiphase brushless DC motor24 connects to a chain, which upon rotation of the motor shaft, movesthe movable barrier 26.

However, in accordance with the preferred embodiment disclosed in FIG.2B, a screw drive configuration 30 is employed. Specifically, the driveassembly 10 also includes a screw drive shaft 32 driven by the brushlessDC motor 24. The screw drive shaft is directly connected to the movablebarrier 26 of the movable barrier assembly. For example, the screw driveshaft 32 may comprise a threaded rod connectable to the rotating shaftof the multiphase brushless DC motor 24. As the motor shaft rotates, thescrew drive shaft 32 rotates. As the screw drive shaft 32 rotates, acarriage, attached to the barrier 26, and having a threaded aperturethat receives the rotating screw drive shaft 32, the carriage thustraveling up and down the threads of the screw drive shaft 32, withcorresponding movement of the movable barrier 26.

With reference to FIG. 3, there is now described a method 100 of movablebarrier movement control implementable with the movable barrier openersystem 2, including the multiphase brushless DC motor 24, as previouslydescribed with reference to FIG. 2A. Accordingly, the controller 18initially receives the externally transmitted command signals from theproximate or remote user-actuated sources previously described, andthereafter parses the data represented by such command signals togenerate the barrier movement instructions that will be sent to thedrive assembly 10. Thus, the first step of the process 100 is theingestion by the controller 18 of the barrier movement instructions asto the desired motor direction, velocity, acceleration, and/or torquecorresponding to the desired movement of a movable barrier 26 (block104).

The controller 18, after the aforementioned parsing, may initiatemovement. Specifically, the controller 18 next provides the barriermovement instructions to the multiphase drive circuit 20, that thendrives the multiphase brushless DC motor 24, which thereby causes themovable barrier 26 to initiate movement (block 106). The controller 18then senses the back EMF via the back EMF sensor module 22 generatingand transmitting the back EMF sensor signal 13 to the controller 18(block 108).

The controller 18, having received the back EMF sensor signal 13 data,and then interpreting the data, calculate the actual operatingparameters, operative parameters as these parameters relate to at leastone of the actual motor torque, direction, and/or other characteristicof the multiphase brushless DC motor 24 (block 110).

Upon calculation of the actual operating parameters, the controller 18determines if the operating parameters are in-tolerance orout-of-tolerance. This means the controller 18 compares the value of atleast one (or more) operating parameter to an expected range of values.This expected range of values may be derived from the movable barrierprofile, from the interpretation matrix, or further may be derived froma table of safe operating parameters separately maintained by thecontroller 18 (block 112).

Upon the operative parameters being determined to be out of tolerance,the method 100 proceeds to block 118, discussed below. Upon the actualoperating parameters being determined to in-tolerance, the controller 18relates the operative parameters to the interpretation matrix tocalculate barrier position metrics (block 114). Calculating barrierposition metrics may include, for example, calculating a position of themovable barrier 26 relative to an end point of travel. Calculatingbarrier position metrics may also include comparing a back EMF of awinding of the multiphase brushless DC motor 24 sampled over time to anelapsed period of time. Because a back EMF may be associated with amotor torque, speed, acceleration, and or the like, this comparisonpermits calculation of a position of the movable barrier. Calculatingbarrier position metrics may further include comparing a multiphasebrushless DC motor 24 torque to a position of the movable barrier 26along the path of travel of the movable barrier 26 and mapping theexperienced torque at the position along the path of travel to anexpected torque at that position. In this manner, further barrierposition metrics such as presence of a fault condition (for instance,presence of an obstruction) may be determined.

Having calculated the barrier position metrics, the controller 18determines the barrier state (block 116). For instance, the controller18 determines whether the barrier position metrics indicate that thebarrier is at a transition state, such as a travel end point, or a pointof acceleration, deceleration, torque change, impinging on anobstruction, undergoing a multiphase brushless DC motor over torquecondition, undergoing a multiphase brushless DC motor overheat conditioncorresponding to a determined over torque and/or the like. Upondetermination that the barrier is not at a transition state, thecontroller 18 determines that no change to the operating parameters isdesired and the movement parameters provided to the multiphase drivecircuit 20 continue unaltered. The method 100 returns to block 108 andback EMF continues to be sensed.

In response to the controller 18 determining that a change to theoperative parameters is desired, for instance, so that the movablebarrier 26 speeds up, slows down, stops, etc., the barrier movementinstructions provided to the multiphase drive circuit 20 are changed bythe controller 18 (block 118). Finally, and specifically in response tothe controller 18 determining that the change of actual operatingparameter that is desired is the stoppage of the movable barrier 26, thecontroller 18 provides barrier movement instructions to cease movementof the movable barrier 26 (block 120).

Thus, one may appreciate that various aspects of the movable barrieropener system 2 interoperate to effectuate a method 100 such asdiscussed above. However, while certain aspects of the method arediscussed in sequence, in various embodiments, aspects of the method mayoccur in parallel. In addition, aspects of the method may occur indifferent sequences.

While the present disclosure has been described in the context ofspecific applications or embodiments, those skilled in the art, havingbenefit of this disclosure, will appreciate that other embodiments canbe envisioned that also embody the new and improved process andapparatus of the present invention, as defined solely by the appendedclaims.

1. A movable barrier opener system comprising: a drive assembly to movea movable barrier in response to barrier movement instructions, thedrive assembly comprising: a multiphase brushless DC motor connectableto the movable barrier to move the movable barrier; a barrier operatorconnected to the drive assembly and comprising: a back EMF sensor moduleto detect a back EMF of a plurality of windings of the multiphasebrushless DC motor and generate a back EMF sensor signal correspondingto the detected back EMF; and a controller configured to receive theback EMF sensor signal and provide the barrier movement instructions tothe drive assembly in response to the back EMF sensor signal.
 2. Themovable barrier opener system of claim 1, the barrier operator furthercomprising: a position sensor module connected to the controller andproviding position sensor data to the controller corresponding to anindication that the movable barrier is at an end point of travel.
 3. Themovable barrier system of claim 1, wherein the drive assembly furthercomprises a multiphase drive circuit connected to the controller toreceive the barrier movement instructions from the controller andconnected to the plurality of windings of the multiphase brushless DCmotor, wherein the multiphase drive circuit is configured to generate aplurality of drive signals corresponding to an excitation of theplurality of windings of the multiphase brushless DC motor.
 4. Themovable barrier opener system of claim 2, wherein the controllerdetermines actual operating parameters of the multiphase brushless DCmotor in response to the back EMF sensor signal, the actual operatingparameters comprising at least one of a motor load, a movable barrierdirection, and a movable barrier position, wherein the controllerrelates the barrier movement instructions and the actual operatingparameters by a transfer function to create a movable barrier profilecomprising tolerances for the actual operating parameters.
 5. Themovable barrier opener system of claim 1, wherein the drive assemblycomprises a screw drive shaft connected to the multiphase brushless DCmotor and rotatable thereby, wherein the movable barrier moves inresponse to the rotation of the screw drive shaft.
 6. The method ofmovement control implementable with a movable barrier opener systemincluding a multiphase brushless DC motor, the method comprising:ingesting, by a controller, barrier movement instructions comprising atleast one of a direction, velocity, acceleration, and torquecorresponding to an intended movement of a movable barrier; initiating,by the controller, movement of the movable barrier connected to themultiphase brushless DC motor, the initiating comprising providing thebarrier movement instructions to a multiphase drive circuit to drive themultiphase brushless DC motor; sensing, by a back EMF sensor moduleconnected to the controller, a back EMF associated with a winding of themultiphase brushless DC motor and transmitting a back EMF sensor signalcorresponding to the sensed back EMF to the controller.
 7. The method ofmovement control according to claim 6, the method further comprisingchanging the barrier movement instructions in response to the back EMFsensor signal.
 8. The method of movement control according to claim 6,the method further comprising: calculating an actual operating parameterof the multiphase brushless DC motor in response to the back EMF sensorsignal.
 9. The method of movement control according to claim 8, whereinthe actual operating parameter comprises at least one of a torque and adirection of the multiphase brushless DC motor that is moving themovable barrier.
 10. The method of movement control according to claim9, the method further comprising: determining that the actual operatingparameter is within a tolerance comprising an expected range of values,calculating a movable barrier position relative to an end point oftravel in response to the said operating parameter; and determining abarrier state corresponding to the movable barrier position.
 11. Themethod of movement control according to claim 10, further comprisingchanging the barrier movement instructions in response to the determinedbarrier state being a transition state.
 12. The method of movementcontrol according to claim 11, wherein the transition state comprises atleast one of an indication that the movable barrier is at a travel endpoint and impinging on an obstruction.
 13. The method of movementcontrol according to claim 11, wherein the transition state comprises atleast one of an indication that the multiphase brushless DC motor isoverheating corresponding to an overtorque condition of the multiphasebrushless DC motor.
 14. A non-transient computer readable mediumcontaining program instructions for causing a movable barrier openersystem including a multiphase brushless DC motor to perform a method ofmovement control, the method comprising: ingesting, by a controller,barrier movement instructions comprising at least one of a direction andtorque instruction corresponding to an intended movement of a movablebarrier; initiating, by the controller, movement of the movable barrierconnected to the multiphase brushless DC motor, the initiatingcomprising providing the barrier movement instructions to a multiphasedrive circuit to drive the multiphase brushless DC motor; and sensing,by a back EMF sensor module connected to the controller, a back EMFassociated with a winding of the multiphase brushless DC motor andtransmitting a back EMF sensor signal corresponding to the sensed backEMF to the controller.
 15. The non-transient computer readable mediumaccording to claim 14, the method further comprising changing thebarrier movement instructions in response to the back EMF sensor signal.16. The non-transient computer readable medium according to claim 14,wherein the method further comprises calculating an actual operatingparameter of the multiphase brushless DC motor in response to the backEMF sensor signal.
 17. The non-transient computer readable mediumaccording to claim 16, wherein the operating parameter comprises atleast one of a torque and a direction of the multiphase brushless DCmotor that is moving the movable barrier.
 18. The non-transient computerreadable medium according to claim 17, further comprising: determiningthat the operating parameter is within a tolerance comprising anexpected range of values, calculating a movable barrier positionrelative to an end point of travel in response to the operativeparameter; and determining a barrier state corresponding to the movablebarrier position.
 19. The non-transient computer readable mediumaccording to claim 18, further comprising changing the barrier movementinstructions in response to the determined barrier state being atransition state.
 20. The non-transient computer readable mediumaccording to claim 19, wherein the transition state comprises at leastone of an indication that the movable barrier is at a travel end point,that the movable barrier is impinging on an obstruction, and that themultiphase brushless DC motor is overheating corresponding to an overtorque condition of the multiphase brushless DC motor.